XPost: comp.theory.cell-automata   
   From: alcore@uurth.com   
   Copy: sci-space-tech@moderators.isc.org   
      
   On Sat, 17 Jul 2004, Simon Hosie wrote:   
      
   >Gene P. wrote:   
   >> Why does every variant of these structures I've read about insist on   
   >> living INSIDE the structure and using spin or unobtainium as a proxy for   
   >> gravity?   
   >>   
   >> Why not live OUTSIDE the shell and let solar gravity hold you down.   
   >   
   >Firstly, is gravity really all that important?  If you're fussing over   
   >all the environmental conditions that make life on earth work right then   
   >you've got bigger problems than gravity.  With the scale of the project,   
   >I'd have thought people would be happy to wait for suitable lifeforms to   
   >evolve.  Although, you risk playing a eugenics game, there.  Is that it?   
   >Is gravity only necessary to avoid the e-word?   
      
   The main reason is to accomodate biosperes of approximately earthlike   
   conditions.   
      
   You are correct that a culture that can build Dyson Spheres is probably   
   capable of redesigning itself and all necessary support elements to   
   tolerate radically different environmental conditions (like zero G).   
      
   I prefer however to design for the species I know.  (Curiously, the   
   airline industry seems to design for smaller humans every year, despite   
   ample demographic evidence that the average American traveller is actually   
   bigger and heavier every year.)   
      
   >Is the shell itself supposed to be weightless?  If not, can't its   
   >gravity be put to some use?  I'm using this here 'Earth' collection   
   >plate at the moment, and it seems to be working out alright.  I haven't   
   >fallen off once.   
      
   Do you mean "massless"?   
      
   I'm assuming that the local gravitational pull of the shell will be   
   insignificant compared to the star's.  (i.e.  I'm assuming that the   
   shell's total mass is small compared to the mass of the star it's   
   surrounding.  Is this a gross error?)   
      
   In effect, the root of the idea was to build a "planet" of stellar mass,   
   and a radius such that it had a 1 g surface gravity.  The "crust" is the   
   shell, and the "core" is an active star.   
      
   I should think that if you used a long-lived low-mass star, that the thing   
   would make an effective inter-galactic generation ship.   
      
   Gene Pharr   
   Slidell, LA   
      
   --   
   Alcore Nilth - The Mad Alchemist of Gevbeck   
   alcore@uurth.com   
      
   --- SoupGate-Win32 v1.05   
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